Method and apparatus for restoring WUP mode for multi-speed ethernet device

ABSTRACT

A method for waking up, from a low-power mode, a first communications node coupled to a second node via a first communication link, includes determining, while the first node is awake, a first transmission rate for transmitting data over the first link, storing the first rate at the second node, and selectively transmitting, from the second node to the first node, a first wake-up command at a symbol rate corresponding to the first rate. Where a third node is coupled to the second node via a second link, the method may further include determining, at the second node, while the third node is awake, a second transmission rate for transmitting data over the second link, storing the second rate at the second node, and selectively transmitting, from the second node to the third node, a second wake-up command at a symbol rate corresponding to the second rate.

FIELD OF USE

This disclosure is related generally to communication networks and, moreparticularly, to generation of wake-up commands.

BACKGROUND

Gigabit Ethernet is designed to transmit Ethernet frames at a rate ofone gigabit per second (1 Gb/s). Gigabit Ethernet uses physical layertransceivers (PHYs) processing devices such as 1000BASE-T1, as definedby the Institute of Electrical and Electronics Engineers (802.3bp)Ethernet standard. A 1000BASE-T1 PHY supports full-duplex operation at 1Gb/s over a single twisted copper wire pair. Similarly, 100BASE-T1 PHYssupport full-duplex operation at 100 megabits per second (100 Mb/s). Insome implementations, 1000BASE-T1 PHYs and 100BASE-T1 PHYs are calledupon to operate in severely constrained environments, such as automotiveand industrial environments in which certain requirements (e.g.,electromagnetic compatibility and temperature requirements) must be met.

It is desirable for 100BASE-T1 PHYs and 1000BASE-T1 PHYs to enter alow-power mode to conserve power consumption and improve the overallefficiency of the automotive or industrial network. One approach toconserve power has been to keep these PHYs in the low-power mode andperiodically waking up the PHY by sending a wake-up signal when the PHYis needed.

SUMMARY

In accordance with implementations of the subject matter of thisdisclosure, a method for waking up a communications node from alow-power mode, the communications node being a first node that iscoupled to a second node via a first communication link, includesdetermining, while the first node is in an awake mode, a first datatransmission rate for transmitting data over the first communicationlink connecting the first node and the second node, storing, at thesecond node, the first data transmission rate, and selectivelytransmitting, from the second node to the first node, a first wake-upcommand at a symbol rate corresponding to the stored first datatransmission rate.

In a first implementation of such a method, the first data transmissionrate may be determined prior to the first node transitioning to thelow-power mode.

In a second implementation of such a method, a third node may be coupledto the second node via a second communication link, and the method mayfurther include determining, at the second node, while the third node isin the awake mode, a second data transmission rate for transmitting dataover the second communication link connecting the third node and thesecond node, storing, at the second node, the second data transmissionrate, and selectively transmitting, from the second node to the thirdnode, a second wake-up command at a symbol rate corresponding to thestored second data transmission rate.

According to a first aspect of the second implementation of such amethod, the first data transmission rate may be different from thesecond data transmission rate.

A second aspect of the second implementation of such a method mayfurther include determining the first data transmission rate and thesecond data transmission rate at a physical layer of the second node.

A third aspect of the second implementation of such a method may furtherinclude storing the first data transmission rate and the second datatransmission rate at a physical layer of the second node.

According to a fourth aspect of the second implementation of such amethod, waking up the first node may include waking up a 100BASE-T1 PHYdevice and waking up the third node may include waking up a 1000BASE-T1PHY device.

In a third implementation of such a method, the first wake up commandmay be configured to transition the first node from the low-power modeto the awake mode.

In a fourth implementation of such a method, determining the first datatransmission rate for transmitting data over the first communicationlink may include determining a transmission rate for a fixedcommunication link.

In a fifth implementation of such a method, storing, at the second node,the first data transmission rate may include storing the first datatransmission rate such that the stored first data transmission rate isaccessible from layer one without accessing higher network layers.

In accordance with implementations of the subject matter of thisdisclosure, a network controller includes control circuitry configuredto determine, while a first node is in an awake mode, a first datatransmission rate for transmitting data over a first communication linkconnecting a first node and the network interface device, and store, atthe network transceiver, the first data transmission rate, andtransceiver circuitry configured to selectively transmit, to the firstnode, at a symbol rate corresponding to the stored first datatransmission rate, a first wake-up command designed to transition thefirst node from a low-power mode.

In a first implementation of such a network controller, the controlcircuitry may be configured to determine the first data transmissionrate prior to the first node transitioning to the low-power mode.

In a second implementation of such a network controller, the controlcircuitry may be further configured to determine, while the first nodeis in the awake mode, a second data transmission rate for transmittingdata over a second communication link connecting a second node and thenetwork controller, and store, at the network controller, the seconddata transmission rate, and the transceiver circuitry may be furtherconfigured to selectively transmit, to the second node, at a symbol ratecorresponding to the stored second data transmission rate, a secondwake-up command designed to transition the second node from a low-powermode.

According to a first aspect of such a second implementation of a networkcontroller, the first data transmission rate may be different from thesecond data transmission rate.

According to a second aspect of such a second implementation of anetwork controller, the control circuitry may be configured to determinethe first data transmission rate and the second data transmission rateat a physical layer of the network controller.

According to a third aspect of such a second implementation of a networkcontroller, the control circuitry may be configured to store the firstdata transmission rate and the second data transmission rate at aphysical layer of the network controller.

According to a fourth aspect of such a second implementation of anetwork controller, the control circuitry may be configured to determinethe first data transmission rate for transmitting data over the firstcommunication link to the first node when the first node comprises a100BASE-T1 PHY device and to determine the second data transmission ratefor transmitting data over the second communication link to the secondnode when the second node comprises a 1000BASE-T1 PHY device.

In a third implementation of such a network controller, the controlcircuitry may be configured to selectively instruct the transceivercircuitry to transmit the first wake-up command as a command that isconfigured to transition the first node from the low-power mode to theawake mode.

In a fourth implementation of such a network controller, the controlcircuitry may be configured to determine the first data transmissionrate for transmitting data over the first communication link to thefirst node when the first communication link is a fixed communicationlink.

In a fifth implementation of such a network controller, the controlcircuitry may be further configured to store, at the network controller,the first data transmission rate such that the stored first datatransmission rate is accessible from layer one without accessing highernetwork layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the disclosure, its nature and various advantages,will be apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

FIG. 1 is a block diagram illustrating an automotive environment havinga number of 100BASE-T1 PHYs and 1000BASE-T1 PHYs which may incorporateimplementations of the subject matter of this disclosure, according tosome implementations described herein;

FIG. 2 illustrates a controller configured to wake up a first PHY and asecond PHY operating at different transmission rates; and

FIG. 3 is a flow diagram illustrating a method according toimplementations of the subject matter of this disclosure.

DETAILED DESCRIPTION

As noted above, gigabit Ethernet is designed to transmit Ethernet framesat a rate of one gigabit per second (1 Gb/s). Gigabit Ethernet usesphysical layer processing devices (PHYs) such as 1000BASE-T1 devices, asdefined by the Institute of Electrical and Electronics Engineers(802.3bp) Ethernet standard. A 1000BASE-T1 PHY supports full-duplexoperation at 1 Gb/s over a single twisted copper wire pair. Similarly,100BASE-T1 PHYs support full-duplex operation at 100 megabits per second(100 Mb/s). In some implementations, 1000BASE-T1 PHYs and 100BASE-T1PHYs are called upon to operate in severely constrained environments,such as automotive and industrial environments in which certainrequirements (e.g., electromagnetic compatibility and temperaturerequirements) must be met.

It is desirable for 100BASE-T1 PHYs and 1000BASE-T1 PHYs to enter alow-power mode to conserve power consumption and improve the overallefficiency of the automotive or industrial network. One approach toconserve power has been to keep these PHYs in the low-power mode andperiodically waking up the PHY by sending a wake-up signal when the PHYis needed.

However, waking up these PHYs presents a challenge in severelyconstrained environments, such as automotive and industrialenvironments. Specifically, when there are PHYs supporting differenttransmission rates (e.g., 1 Gb/s for 1000BASE-T1 PHYs and 100 Mb/s for100BASE-T1 PHYs), the controller of the network must efficiently wake upthese devices when they are needed. Additionally, when there isinterference, such as in an automotive environment, it may be necessaryto reduce the affective transmission rate relative to the nominaltransmission speed rating. This reduced rate may be unknown andconventionally would require a time-consuming handshake procedure todetermine the optimal speed at which the device can operate in the noisyenvironment. In many environments, such as automotive environments, itis important that devices are awakened from a low-power state as quicklyas possible.

In the current specification of the automotive Ethernet Wake/Sleepfunction according to Technical Committee 10 (TC10) of the OPEN AllianceSpecial Interest Group, each different data transmission speed has itsown wake-up (WUP) command (a pulse or series of pulses, or othersuitable bit sequence, to be sent to wake up a link partner when thelink partner is in sleep mode).

If auto-negotiation is not in use, and a PHY were to support both100BASE-T1 and 1000BASE-T1 speeds, then typically the wake-up commandused would be the wake-up command corresponding to thehardware-configured speed. However, if auto-negotiation is enabled, thenwhen a multi-speed device (such as a controller) is partnered with anon-lowest speed device (e.g., a 1000BASE-T1 PHY), and the devicesperform the sleep/wake-up function, the multi-speed deviceconventionally will use the WUP command for the lowest advertised speed(e.g., 100 Mb/s for a 100BASE-T1 PHY), which may not be a match for somelink partners and might not be able to wake up those link partners.

Accordingly, there is a need for an efficient mechanism for waking up,from a respective low-power mode, PHYs having different transmissionrates, particularly when auto-negotiation is in use.

In accordance with implementations of the of the subject matter of thisdisclosure, a controller (e.g., an Electronic Control Unit (ECU) asshown in FIG. 1 ) is configured to determine a first data transmissionrate between the ECU and a first PHY. For instance, the datatransmission rate may be determined during link training by transmittingone or more data packets over a fixed communication link connecting thetwo devices. Once the first data transmission rate is determined, therate is stored at the physical layer of the controller. In someimplementations, if the transmission rate changes during operation(e.g., because of changing conditions on the communication pathway), thestored first data transmission rate may be updated. Thereafter, whenwaking up the first PHY from a low-power mode, the controller retrievesthe stored first data transmission rate, and transmits the wake-upcommand at a symbol rate corresponding to the first data transmissionrate most recently used on the particular link.

The controller and the first PHY may be part of a larger system ornetwork including additional PHYs that communicate with the controller.However, determination of the appropriate wake-up command is madeseparately for each individual PHY. The controller thus treats each PHYin the system or network individually, determining a respective datatransmission rate for each of the PHYs within the network and separatelystoring the respective data transmission rates. If any individual PHYenters sleep mode and needs to be awakened, the controller may look upand use the respective data transmission rate to send an appropriatewake-up commands at a respective appropriate symbol rate correspondingto the respective data transmission rate.

Upon the initial power-up of any link, a preconfigured value that can beused to wake up the PHYs from a low-power mode is established throughlink training. Once the transmission link is up, the speed of the PHYwhen the link is established is stored at the physical layer of the ECUand is retained during both wake-up and sleep conditions by amulti-speed device (ECU). Afterwards, if the sleep/wake-up function isperformed, when the multi-speed device is ready to wake the other PHYswithin the network, the stored most recently wake-up speed of eachprevious link-up prior to sleep is used to determine the proper WUP modeto transmit. The WUP mode of the multi-speed device therefore ensuresthat the wake-up command will automatically be compatible for the linkpartner by using the previously stored data transmission rate. Thepossibility of WUP mode mismatch is reduced, and interoperability isenhanced.

In a possible alternative implementation, a new data transmission ratemay be determined between a wake-up event and a sleep event if channelconditions degrade. In order to efficiently and rapidly wake up thesleeping link partner at the most recently used rate, that most recentlyused rate may be stored at the physical layer of the multi-speed device(ECU) prior to a device entering low-power mode. In such an alternativeimplementation the link partner would be programmed to accept differentwake-up commands for different speeds, and the multi-speed device wouldissue the wake-up command corresponding to the most recently used speed.In this way, on a wake-up event, the link could be brought up at thecorrect speed in the first instance, rather than being brought up at thedefault speed of the link partner and having to be negotiated down to alower speed based on conditions. This possible alternativeimplementation will be discussed in further detail below.

The subject matter of this disclosure will be better understood byreference to FIGS. 1-3 .

FIG. 1 is a block diagram illustrating an automotive environment havinga number of 100BASE-T1 PHYs and 1000BASE-T1 PHYs which may incorporateimplementations of the subject matter of this disclosure, according tosome implementations described herein. In the example implementationshown in FIG. 1 , the automotive network 100 includes an ElectronicControl Unit (ECU) 102 (multi-speed device), 100BASE-T1 PHYs (displays104, a DVD player 106, amplifiers 108, and cameras 110), and a1000BASE-T1 PHY (Driver Assist Unit 112). Any number of 100BASE-T1 PHYsand 1000BASE-T1 PHYs can be included within the automotive network 100of FIG. 1 in different implementations. Additional components of themulti-speed device, 100BASE-T1 PHYs, and 1000BASE-T1 PHYs are discussedin greater detail below in connection with FIG. 2 .

In accordance with implementations of the subject matter of thisdisclosure, ECU 102, when communicating with the various 100BASE-T1 PHYsand 1000BASE-T1 PHYs, determines a respective data transmission rate foreach of the PHYs and stores it—e.g., in a register—at the physical layerof ECU 102. For instance, ECU 102 stores a first data transmission ratecorresponding to camera 110 while storing a second data transmissionrate corresponding to Driver Assist Unit 112. In accordance with oneimplementation, the second data transmission rate is higher than thefirst data transmission rate.

When waking up cameras 110 from a low-power mode, ECU 102 generates afirst wake-up command and transmits it to cameras 110 at a symbol ratecorresponding to the first data transmission rate (e.g. 100 Mb/s).Similarly, when waking up Driver Assist Unit 112 from a low-power mode,ECU 102 generates a second wake-up command and transmits it to DriverAssist Unit 112 at a symbol rate corresponding to the second datatransmission rate (e.g. 1000 Mb/s). In accordance with oneimplementation, ECU 102 determines and stores the respective datatransmission rates prior to each of the PHYs transitioning to thelow-power mode.

FIG. 2 is a high-level block diagram of two 1000BASE-T1 PHYs with whichimplementations of the subject matter of this disclosure may be used. Asshown in FIG. 2 , a multi-speed device 202 (e.g., ECU 102) includes atransceiver 204, a transmitter rate determiner 206, a memory 208, and awake-up detector 210.

A first PHY 212 (e.g., each one of cameras 110) to be awakened includesa wakeup detection block 214 and transceiver main blocks 216. Inaccordance with an embodiment of the subject matter of this disclosure,PHY 202 is connected to PHY 212 by a single twisted pair of cables.

A second PHY 218 (e.g., Driver Assist unit 112) to be awakened includesa wakeup detection block 220 and transceiver main blocks 222. Inaccordance with an embodiment of the subject matter of this disclosure,PHY 202 is connected to PHY 218 by a single twisted pair of cables.

Upon an initial power-up event, ECU 202 has preconfigured datatransmission rates corresponding to first PHY 212 and second PHY 218.ECU 102 begins transmitting data to first PHY 212 and second PHY 218 attheir respective preconfigured values via transceiver 204. During anauto-negotiation process between ECU 202, first PHY 212, and second PHY218, ECU 202, via transmitter rate determiner 206, determines arespective data transmission rates corresponding to each of the firstPHY 212 and second PHY 218. The respective data transmission rates arethen stored in memory 208 for subsequent use when waking up first PHY212 and second PHY 218 from a low-power mode.

More specifically, when ECU 202 needs to wake up first PHY 212 andsecond PHY 218, transceiver 204 retrieves the stored respective datatransmission rates corresponding to each of first PHY 212 and second PHY218 from memory 208. Wake-up detector 210 generates a wake-up commandand transceiver 204 transmits the wake-up command at a symbol ratecorresponding to the respective data transmission rates to first PHY 212and second PHY 218. In one implementation, transceiver 204 transmits thewake-up command to first PHY 212 (100BASE-T1 PHY) at a symbol rate of66⅔ MHz per symbol. In addition, transceiver 204 transmits the wake-upcommand to second PHY 218 (1000BASE-T1 PHY) at a symbol rate of 62.5 MHzper symbol. The wakeup detection block 214 of first PHY 212, in responseto receiving its respective wake-up command, begins the wake-up processvia the transceiver main blocks 216. Similarly, wake-up detection block220 of second PHY 218, in response to receiving its respective wake-upcommand, begins the wake-up process via the transceiver main blocks 222.

Transmission rates may deviate from the rated transmission rates. Forexample, transmission rates may become reduced because of interferenceaffecting a link. Therefore, in the possible alternative implementationreferred to above, the last transmission rate prior to a link partnerentering a low-power mode is determined and stored in memory. In such analternative implementation, each respective wake-up detection block 214,220 would be programmed to accept different wake-up commands fordifferent speeds, and the multi-speed device would issue the wake-upcommand corresponding to the most recently used speed. In this way, on awake-up event, the link could be brought up at the correct speed in thefirst instance, rather than being brought up at the default speed of thelink partner and having to be negotiated down to a lower speed based onconditions.

FIG. 3 is a flow diagram illustrating a method according toimplementations of the subject matter of this disclosure for storing asymbol rate for waking up a device as described above.

At 301, a transmission rate between a first node and a second node isdetermined. Optionally at 302, data is transmitted from the second nodeto the first node at the determined transmission rate (although a methodaccording to implementations of the subject matter of this disclosurecan operate even if no actual data transmission occurs during aparticular sleep/wake session). The transmission rate is stored at thesecond node at 303. At 304, the symbol rate corresponding to this storedtransmission rate is used for transmitting a wake-up command from thesecond node to the first node.

Thus is it seen that a method for waking up devices in a wirelinenetwork, the devices having different respective operating speeds, hasbeen provided.

While various embodiments of subject matter of the present disclosurehave been shown and described herein, such embodiments are provided byway of example only. Numerous variations, changes, and substitutionsrelating to embodiments described herein are applicable withoutdeparting from the subject matter of the disclosure. It is noted thatvarious alternatives to the embodiments of the subject matter of thedisclosure described herein may be employed in practicing the subjectmatter of the disclosure. It is intended that the following claimsdefine the scope of the subject matter of the disclosure and thatmethods and structures within the scope of these claims and theirequivalents be covered thereby.

While operations are depicted in the drawings in a particular order,this is not to be construed as requiring that such operations beperformed in the particular order shown or in sequential order, or thatall illustrated operations be performed to achieve the desirableresults.

The subject matter of this disclosure has been described in terms ofparticular aspects, but other aspects can be implemented and are withinthe scope of the following claims. For example, the actions recited inthe claims can be performed in a different order and still achievedesirable results. In certain implementations, multitasking and parallelprocessing may be advantageous. Other variations are within the scope ofthe following claims.

What is claimed is:
 1. A method for waking up a communications node froma low-power mode, the communications node being a first node that iscoupled to a network controller via a first communication link, themethod comprising: determining, while the first node is in an awakemode, a first data transmission rate for transmitting data over thefirst communication link connecting the first node and the networkcontroller; storing, at the network controller, the first datatransmission rate; and selectively transmitting, from the networkcontroller to the first node, a first wake-up command at a symbol ratecorresponding to the stored first data transmission rate.
 2. The methodfor waking up a communications node according to claim 1, wherein thefirst data transmission rate is determined prior to the first nodetransitioning to the low-power mode.
 3. The method for waking up acommunications node according to claim 1, wherein a third node iscoupled to the network controller via a second communication link, themethod further comprising: determining, at the network controller, whilethe third node is in the awake mode, a second data transmission rate fortransmitting data over the second communication link connecting thethird node and the network controller; storing, at the networkcontroller, the second data transmission rate; and selectivelytransmitting, from the network controller to the third node, a secondwake-up command at a symbol rate corresponding to the stored second datatransmission rate.
 4. The method for waking up a communications nodeaccording to claim 3, wherein the first data transmission rate isdifferent from the second data transmission rate.
 5. The method forwaking up a communications node according to claim 3, further comprisingdetermining the first data transmission rate and the second datatransmission rate at a physical layer of the network controller.
 6. Themethod for waking up a communications node according to claim 3, furthercomprising storing the first data transmission rate and the second datatransmission rate at a physical layer of the network controller.
 7. Themethod for waking up a communications node according to claim 3, whereinwaking up the first node comprises waking up a 100BASE-T1 PHY device andwaking up the third node comprises waking up a 100BASE-T1 PHY device. 8.The method for waking up a communications node according to claim 1,wherein the first wake-up command is configured to transition the firstnode from the low-power mode to the awake mode.
 9. The method for wakingup a communications node according to claim 1, wherein determining thefirst data transmission rate for transmitting data over the firstcommunication link comprises determining a transmission rate for a fixedcommunication link.
 10. The method for waking up a communications nodeaccording to claim 1, wherein storing, at the network controller, thefirst data transmission rate comprises storing the first datatransmission rate such that the stored first data transmission rate isaccessible from layer one without accessing higher network layers.
 11. Anetwork controller comprising: control circuitry configured to:determine, while a first node is in an awake mode, a first datatransmission rate for transmitting data over a first communication linkconnecting a first node and the network controller, and store, at thenetwork controller, the first data transmission rate; and transceivercircuitry configured to: selectively transmit, to the first node, at asymbol rate corresponding to the stored first data transmission rate, afirst wake-up command designed to transition the first node from alow-power mode.
 12. The network controller according to claim 11,wherein the control circuitry is configured to determine the first datatransmission rate prior to the first node transitioning to the low-powermode.
 13. The network controller according to claim 11, wherein: thecontrol circuitry is further configured to: determine, while a secondnode is in the awake mode, a second data transmission rate fortransmitting data over a second communication link connecting the secondnode and the network controller, and store, at the network controller,the second data transmission rate; and the transceiver circuitry isfurther configured to selectively transmit, to the second node, at asymbol rate corresponding to the stored second data transmission rate, asecond wake-up command designed to transition the second node from alow-power mode.
 14. The network controller according to claim 13,wherein the first data transmission rate is different from the seconddata transmission rate.
 15. The network controller according to claim13, wherein the control circuitry is configured to determine the firstdata transmission rate and the second data transmission rate at aphysical layer of the network controller.
 16. The network controlleraccording to claim 13, wherein the control circuitry is configured tostore the first data transmission rate and the second data transmissionrate at a physical layer of the network controller.
 17. The networkcontroller according to claim 13, wherein the control circuitry isconfigured to determine the first data transmission rate fortransmitting data over the first communication link to the first nodewhen the first node comprises a 100BASE-T1 PHY device and to determinethe second data transmission rate for transmitting data over the secondcommunication link to the second node when the second node comprises a1000BASE-T1 PHY device.
 18. The network controller according to claim11, wherein the control circuitry is configured to selectively instructthe transceiver circuitry to transmit the first wake-up command as acommand that is configured to transition the first node from thelow-power mode to the awake mode.
 19. The network controller accordingto claim 11, wherein the control circuitry is configured to determinethe first data transmission rate for transmitting data over the firstcommunication link to the first node when the first communication linkis a fixed communication link.
 20. The network controller according toclaim 11, wherein the control circuitry is further configured to store,at the network controller, the first data transmission rate such thatthe stored first data transmission rate is accessible from layer onewithout accessing higher network layers.